When the first Austrian stamps appeared in 1850 to a population of 36 million, only a quarter of the population spoke German. Slavs outnumbered German speakers by 2:1. At different times around nine official languages existed and more than a dozen minority languages or trade lingua francas. The Post Office and the railways were two strategic infrastructures that were used to weld the Empire together in the 19th century.
In the Levant, postal connections were opened at ports and consular offices from northern Turkey to Palestine.
The rapid development of Hungary led to a form of UDI in 1867. They remained within the Hasburg dual monarchy, but gained full control of their internal affairs, including taxation and stamps.
So, postmarks play a big part in the story of the consolidation of Empire and demonstrate its far-flung reach. Additionally quite a range of postmark design and formats, and red and blue inks, make the postmarks very attractive to collect.
Within the State Printing Works were a quantity of printing machines, most assembled with different perforation measurements, and used at random as work permitted. Even Gibbons gives up and just states "various compounds of 9 to 13½" when their heads started spinning!
So, whether you collect Austria for the social and historical interest, or for the technical challenge of postmarks and perforations, there's plenty to explore between 1850 and 1918. If you want to go beyond Gibbons, the massive Ferchenbauer in four volumes covers just this Empire period.
If you would like to learn more and meet other collectors of Austrian stamps, I suggest joining the Austrian Philatelic Society. Members receive a journal covering all aspects from prestamp to new issues, a library, meetings (when permitted), and from time to time, an auction.
Membership Secretary there is Nick Coverdale, 38 Hillcrest. Whitehaven, Cumbria CA28 6ST. Email : firstname.lastname@example.org